San Francisco Giants pitcher Tim Lincecum walks to the dugout at the end of the first inning allowing Oakland Athletics Ryan Sweeney to scores,Friday June 11, 2010, in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco Giants pitcher Tim Lincecum walks to the dugout at...

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San Francisco Giants starting pitcher Tim Lincecum, left, and catcher Bengie Molina celebrate after the Giants' 10-0 victory over the St. Louis Cardinals in a baseball game Monday, June 29, 2009, in St. Louis. Lincecum threw a two-hitter. (AP Photo/Jeff Roberson)

Photo: Jeff Roberson, AP

San Francisco Giants starting pitcher Tim Lincecum, left, and...

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PEORIA, AZ - MARCH 03: Buster Posey #28 of the San Francisco Giants catches against the Seattle Mariners during a spring training game at Peoria Sports Complex on March 3, 2010 in Peoria, Arizona. (Photo by Chris McGrath/Getty Images)

"He said this is part of the game," Tim Lincecum recalled. "He said, 'I love you guys. That's how it goes.' "

Lincecum confessed it was emotional for him, saying, "I don't think I was ready to cry or anything. It's just tough to watch him go."

The deal - Molina to Texas for reliever Chris Ray and minor-league prospect Michael Main - became official Thursday afternoon. General manager Brian Sabean cited several reasons for the deal, but the chief reason was to clear the way for Buster Posey to become the everyday catcher.

"Quite frankly, we've got to figure a way to get Buster in there more on a regular basis, and this allows us to do that," Sabean said.

"Make no mistake. He's in there to get the playing time as much as possible, especially behind home plate. I think the timing is good to introduce Buster, and the timing is good to go on to the next level of conversation, how we're going to bring somebody else in here," presumably a left-handed bat.

Manager Bruce Bochy said Posey will not catch a lot of games initially because Bochy wants the more experienced Eli Whiteside to help a struggling pitching staff get back on track. Whiteside will catch Lincecum tonight.

"With Buster not catching a lot, it's not a case where he can come in and catch every day," said Bochy, who nonetheless paired Posey with Madison Bumgarner on Thursday night.

With Molina gone, the onus falls more on the pitchers to run the show, especially with Posey catching.

"It essentially comes down to us as pitchers making sure we have the right pitches to throw," Cain said. "If (the catcher) puts something down, we throw it and we didn't want to throw it, that's our fault. The game is in our hands."

Lincecum often said he wished he could carve his Cy Young awards in half so Molina could get a share. But he added, "I have worked with Buster, obviously not many games at the major-league level. He caught my (second-to-last) start last year. Whitey's caught me a few times. This is a game where you have to evolve and adapt."

Posey said he "definitely" feels ready to catch every pitcher on the staff, which will grow to 13 with Ray's arrival and perhaps stay that way as the Giants play 11 consecutive games on the road.

"It's not like this will be the first time I'll be catching any of these guys."

In return for Molina, the Giants received Ray, a right-handed reliever and former Orioles closer who will to audition for a late-relief job. The Giants also get 21-year-old starter Main, a first-round draft pick in 2007 who struggled through mononucleosis last year, but whom the Rangers promoted from Single-A to Double-A just before the trade.

In explaining the trade, Sabean said that, in addition to wanting to put Posey behind the plate, the Giants could use another reliever, they like Main and Molina was not hitting. After driving in 81, 95 and 80 runs in his three full seasons in San Francisco, Molina was batting .257 with three homers and 17 RBIs in 202 at-bats this year.

The Giants had re-signed him to a guaranteed $4.5 million contract this winter because they believed Posey was not ready to catch full time. The Giants will send Texas the remainder of Molina's salary minus the rest of Ray's - about $2 million.

Molina had seemed more withdrawn in the clubhouse. Management wondered if he was down because he did not get the multiyear deal he sought in the offseason. He openly talked about retirement.

"He's certainly capable of bouncing back," Sabean said. "The other thing is, he's going to a better lineup. I think he has a chance to break out of this rut that he's been in. He has hit, so to speak, but the run production wasn't there, and finding out where to hit him in the order became a struggle for both parties."

Here's the catch

A catcher is more than just one of nine players on the field, which is why Bengie Molina's departure after 3 1/2 seasons and the ascent of Buster Posey, below, represent such a radical shift.

Command center

The catcher calls the pitches, though the pitcher can shake him off.

Therefore, the catcher:

-- Is expected to know the tendencies of every pitcher on his team's staff.

-- Must know for every opposing hitter: which pitches he likes to hit and can't hit, which locations to aim for and which to stay away from.

Pitching coach

The catcher essentially is an assistant pitching coach.

Therefore, catching duties include:

-- Calming a pitcher who gets excited.

-- Firing up a pitcher who gets lackadaisical.

-- Reminding pitchers to hold runners.

-- Correcting pitchers when mechanical flaws are evident.

In sum

Pitchers such as Tim Lincecum and Matt Cain relied heavily on Molina's expertise and counsel.

"I know the things he's done for me," Cain said, "calling games and giving me the confidence to throw different pitches in different counts. It really benefited me. Everything he's done in his 3 1/2 years here is going to help all of us, not just me."